U.S. patent number 6,748,796 [Application Number 10/130,717] was granted by the patent office on 2004-06-15 for procedure for determining the dynamic behavior of a vehicle on a test bench.
This patent grant is currently assigned to Krypton Electronic Engineering N.V.. Invention is credited to Alex Van Den Bossche.
United States Patent |
6,748,796 |
Van Den Bossche |
June 15, 2004 |
Procedure for determining the dynamic behavior of a vehicle on a
test bench
Abstract
A method for measuring the displacement of a vehicle wheel
relative to the frame thereof or relative to a fixed point of
reference. The vehicle is located on a test stand in which the
wheel is loaded, statically or dynamically. In a first step, a
measuring system including cameras measures the position of at
least three points of reference on the wheel, these three points of
reference not being in a straight line. In a second step, the
relative displacement of the wheel is calculated.
Inventors: |
Van Den Bossche; Alex
(Walshoutem, BE) |
Assignee: |
Krypton Electronic Engineering
N.V. (Leuven, BE)
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Family
ID: |
3892177 |
Appl.
No.: |
10/130,717 |
Filed: |
May 23, 2002 |
PCT
Filed: |
November 24, 2000 |
PCT No.: |
PCT/BE00/00139 |
PCT
Pub. No.: |
WO01/38843 |
PCT
Pub. Date: |
May 31, 2001 |
Foreign Application Priority Data
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Nov 24, 1999 [BE] |
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9900765 |
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Current U.S.
Class: |
73/116.01;
33/288; 73/114.06 |
Current CPC
Class: |
G01B
11/2755 (20130101); G01M 17/04 (20130101); G01B
2210/143 (20130101); G01B 2210/146 (20130101); G01B
2210/16 (20130101); G01B 2210/22 (20130101); G01B
2210/30 (20130101) |
Current International
Class: |
G01B
11/275 (20060101); G01M 17/04 (20060101); G01M
17/007 (20060101); G01M 015/00 () |
Field of
Search: |
;73/11.05,11.04,11.07,11.08,11.09,118.1 ;340/438,442,443
;33/286,288,335,336,337 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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4212426 |
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Jul 1993 |
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DE |
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19757760 |
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Jul 1999 |
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DE |
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19757763 |
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Jul 1999 |
|
DE |
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19823367 |
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Nov 1999 |
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DE |
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0390710 |
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Oct 1990 |
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EP |
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0803703 |
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Oct 1997 |
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EP |
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WO 0107862 |
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Feb 2001 |
|
WO |
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Other References
Abstract of JP-09133510 published May 20, 1997..
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Primary Examiner: McCall; Eric S.
Attorney, Agent or Firm: Browdy and Neimark, P.L.L.C.
Claims
What is claimed is:
1. A method for measuring displacement of a wheel of a vehicle
relative to the frame of the vehicle, or relative to a fixed point
of reference when the vehicle is located on a test stand in which
the vehicle is loaded, statically or dynamically, comprising: a.
measuring each position of each of three points of reference on the
wheel, said points of reference not lying in a straight line, by
means of a measuring system comprising cameras; b. measuring
positions of three points of reference provided on the frame; and
c. calculating the displacement of the wheel relative to the
frame.
2. The method according to claim 1 wherein, prior to step (a), the
wheel is revolved about the axis of rotation of the wheel, while
successive positions of at least one of the points of reference on
the wheel are measured on a traced arc through the point of
reference under consideration in which a plane is defined which is
parallel to the arc and wherein the center of the circle on which
the arc lies on which lies on the axis of rotation is calculated,
so as to determine a coordinate system, the first axis of which
coincides the with axis of rotation and a second and a third axis
lie in the said plane.
3. The method according to claim 2 wherein the coordinate system is
displaced along the direction of the axis of rotation over a known
distance such that the plane coincides with the median transverse
vertical plane of the wheel.
4. The method according to claim 2 wherein the position of the
points of reference of several wheels of the vehicle in a state of
rest is determined relative to one another such that these points
of reference can be expressed in terms of the same coordinate
system.
5. The method according to claim 3 wherein the position of the
points of reference of several wheels of the vehicle in a state of
rest is determined relative to one another such that these points
of reference can be expressed in terms of the same coordinate
system.
6. The method according to claim 1 wherein the position of at least
three points of reference of the frame is measured, in which the
relative position of the points of reference of the wheel relative
to the points of reference of the frame is calculated, such that
the exact position of the wheel is known relative to the frame.
7. The method according to claim 2 wherein the position of at least
three points of reference of the frame is measured, in which the
relative position of the points of reference of the wheel relative
to the points of reference of the frame is calculated, such that
the exact position of the wheel is known relative to the frame.
8. The method according to claim 3 wherein the position of at least
three points of reference of the frame is measured, in which the
relative position of the points of reference of the wheel relative
to the points of reference of the frame is calculated, such that
the exact position of the wheel is known relative to the frame.
9. The method according to claim 4 wherein the positions of at
least three points of reference of the frame is measured, in which
the relative position of the points of reference of the wheel
relative to the points of reference of the frame is calculated,
such that the exact position of the wheel is known relative to the
frame.
10. The method according to claim 1 wherein the wheel is loaded at
a frequency between 10 Hz and 500 Hz.
11. The method according to claim 2 wherein the wheel is loaded at
a frequency between 10 Hz and 500 Hz.
12. The method according to claim 3 wherein the wheel is loaded at
a frequency between 10 Hz and 500 Hz.
13. The method according to claim 4 wherein the wheel is loaded at
a frequency between 10 Hz and 500 Hz.
14. The method according to claim 6, wherein the wheel is loaded at
a frequency between 10 Hz and 500 Hz.
15. The method according to claim 1 wherein linear cameras are used
in the measuring system.
16. The method according to claim 2 wherein linear cameras are used
in the measuring system.
17. The method according to claim 3 wherein linear cameras are used
in the measuring system.
18. The method according to claim 4 wherein linear cameras are used
in the measuring system.
19. The method according to claim 5 wherein linear cameras are used
in the measuring system.
20. The method according to claim 6 wherein linear cameras are used
in the measuring system.
21. The method according to claim 1 wherein infrared diodes are
used for the point of reference.
22. The method according to claim 2 wherein infrared diodes are
used for the point of reference.
23. The method according to claim 3 wherein infrared diodes are
used for the point of reference.
24. The method according to claim 4 wherein infrared diodes are
used for the point of reference.
25. The method according to claim 5 wherein infrared diodes are
used for the point of reference.
26. The method according to claim 1 wherein infrared diodes are
used for the point of reference.
27. The method according to claim 2 wherein infrared diodes are
used for the point of reference.
28. The method according to claim 2 wherein infrared diodes are
used for the point of reference.
29. The method according to claim 4 wherein infrared diodes are
used for the point of reference.
30. The method according to claim 6 wherein infrared diodes are
used for the point of reference.
31. The method according to claim 10 wherein infrared diodes are
used for the point of reference.
32. The method according to claim 15 wherein infrared diodes are
used for the point of reference.
Description
FIELD OF THE INVENTION
The invention relates to a method for measuring the displacement of
a wheel of a vehicle relative to the frame thereof or relative to a
fixed point of reference, when this vehicle is located on a test
stand, in which the vehicle, preferably via the said wheel is
loaded, statically or dynamically.
BACKGROUND OF THE INVENTION
According to the present state of the art, such measurements are
taken using linear inductive wheel motion recorders, laser
projection sensors or milometers on the basis of unwinding reels of
cord in conjunction with a rotary encoder.
All these commonly-used measuring systems and the test methods have
the drawback that only a limited excitation of the wheel can be
measured. Hence, on account of the technical features of the
existing measuring systems, only a maximum rotation or inclination
of the wheel in the region of 20 degrees can be measured. In
addition, these existing systems are no good for taking
measurements if and when the wheel is loaded at a frequency which
is higher than 10 Hz or if this wheel is subjected to large
excitations.
These existing test set-ups are extremely complex in their design,
hard to calibrate and it is, on top of that, very laborious to
build in additional points of reference on the frame.
SUMMARY OF THE INVENTION
The aim of the method, according to the invention, is to remove
these drawbacks and to propose a method which allows measurements
to be taken at very high frequencies and with very large
displacements of the wheel relative to the frame. With this method
it is also possible to measure very large rotations or inclinations
of the wheel.
In addition the method, according to the invention, offers the
added advantage that, in a straightforward way, a high number of
extra points of reference can be incorporated in the frame. These
points of reference can be depicted in a shared system of
coordinates relative to one and the same coordinate system.
To this aim, in the method according to the invention, in a first
step, the position of at least three, not lying in a straight line,
points of reference on the said wheel are measured by means of a
measuring system which, preferably, comprises linear cameras or
matrix cameras, in which subsequently, in a second step, the said
relative displacement is calculated.
To this end, prior to the first step, the said wheel is subjected
to a revolution about the axis of rotation thereof while successive
positions of at least one of the points of reference are measured
on the thus, through the point of reference under consideration,
traced arc, in which, on the one hand, a plane is defined which is
parallel to this arc and, on the other hand, the centre of the
circle on which the arc lies and which lies on the said axis of
rotation is calculated, so as to determine a coordinate system
whose first axis coincides with the axis of rotation and a second
and third axis lie in the said plane.
In a preferred embodiment of the method, according to the
invention, the said coordinate system is displaced along the
direction of the axis of rotation over a known distance such that
the said plane coincides with the median transverse vertical plane
of the wheel.
According to a special embodiment of the method, according to the
invention, the position of the points of reference of several
wheels of the said vehicle in a state of rest is determined
relative to one another such that the positions of these points of
reference can be expressed in terms of one and the same coordinate
system.
Other peculiarities and advantages of the invention will soon
become apparent from the following description of a specific
embodiment of the method and the configuration according to the
invention; this description is only given as an example and does
not limit the scope of the protection that is being claimed; the
reference numbers used hereinafter bear upon the figures appended
hereto.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic perspective drawing of part of a test stand
showing part of a vehicle.
FIG. 2 is a schematic representation of a wheel with three points
of references in side elevation.
FIG. 3 is a schematic representation of the wheel out of FIG. 2
viewed end-on.
FIG. 4 is a schematic top view of a test stand with a vehicle on
it.
In the various figures, the same reference numbers bear upon the
same or analogous elements.
In the method, according to the invention, a vehicle, e.g. a car,
of which, for example, the wheel suspension is to be tested, is set
upon a test stand. This test stand is equipped with actuators which
mean that at least one wheel of the vehicle can be exited such that
the wheel is subjected to a translatory movement and/or a
rotation.
Represented schematically, in FIG. 1, is such an actuator 1 on
which a wheel 2 rests of a vehicle 3.
In the method, according to the invention, three points of
reference 4 and fitted to the side surface of the wheel 2. These
points of reference 4 consist of light-emitting diodes (LEDs). Also
mounted on the frame 5 of the vehicle 3 are three points of
reference 6 each of which, like before, consists of a
light-emitting diode (LED).
DETAILED DESCRIPTION OF THE INVENTION
After that, the said actuator 1 is activated and a specified
excitation is imposed on the wheel 2.
In order to determine the displacement of the wheel 2 relative to
the frame 5 of the vehicle 3, are measured, in a first step, using
a measuring system 7, which comprises three linear cameras 8, the
position of the points of reference 4 of the wheel 2 and the points
of reference 6 of the frame 5.
The use of a measuring system 7 with linear cameras 8 means that
the position of the points of reference 4 and 6 can be measured at
very high speed and with great precision, such that measurements
can be carried out for excitations of the wheel 2 at frequencies up
to 500 Hz. These linear cameras 8 make it, for instance, possible
to operate at 3,000 measurements per second.
Such a high-frequency measuring system is, in itself, well-known
and an analogous measuring system was set down in the Belgian
patent application No. 09700143.
Starting from each position thus measured for the three points of
reference 4 of the wheel 2 and for the three points of reference 6
of the frame 5 is then calculated, in a second step, the
displacement of the wheel 2 relative to the frame 5 using already
well-documented trigonometry.
In an alternative embodiment of the method, according to the
invention, the displacement of the wheels 2 and the frame 5 are
determined relative to a fixed point of reference, for example the
test stand itself.
In a preferred embodiment of the method, according to the
invention, is set up, prior to the above-mentioned first step, a
coordinate system which is fixed with respect to the wheel 2, whose
displacement relative to the frame 5 is to be determined.
Firstly, to that end, a plane is determined which is perpendicular
to the axis of rotation of the wheel 2 in question and, after that,
a centre of rotation of this axis of rotation is calculated. In
this way the axis of rotation itself of the wheel 2 can be
calculated exactly as this axis is at right angles to the said
plane and runs through the centre of rotation.
In a first variant on the method are measured, for the
determination of this plane, by means of the measuring system, the
position of each of the three points of reference 4 of the wheel 2.
The plane is then determined which contains these three points of
reference 4.
The points of reference 4 are measured, preferably, by means of a
set-up and method as outlined in the Belgian patent application No.
9700366.
In a second variant on the method, the position of the said plane
is determined by subjecting the wheel 2 to a revolution about the
axis of rotation thereof and passing through 180 degrees, as shown
schematically in FIG. 2. During this rotary motion, successive
positions are measured of at least one point of reference 4. These
measured positions all lie along an arc 9. Finally, the plane is
determined that contains this arc 9.
Also, in order to determine the correct position of the said centre
of rotation, the centre 10 of the circle on which the arc 9 lies,
is calculated. As a consequence, the said centre of rotation
coincides with this centre 10.
Next, a coordinate system 11 is defined whose first axis 12 is
perpendicular to the said plane and which contains the said centre
of rotation so that this axis 12 coincides with the axis of
rotation of the wheel 2. A second and third axis 13 and 14 of this
coordinate system 11 are perpendicular to each other and, together,
from the said plane that was determined according to one of the
variant versions as described above.
According to a special preferred embodiment of the method,
according to the invention, the said coordinate system 11 is then
moved through a known distance according to the axis of rotation of
the wheel 2, such that the said second and third axes 13 and 14
constitute the medium transverse vertical plane 15 of the wheel 2,
as shown in FIG. 3.
If the point of reference 4 of the wheel 2 is mounted on the side
surface thereof, the coordinate system 11 should, as a consequence,
be moved, through a distance which is equal to the half the
thickness of the wheel 2.
As and when the said actuator 1 excites the wheel 2, are measured,
almost continuously, the position of the points of reference 4 of
the wheel 2 and the points of reference 6 of the frame 5 by the
measuring system 7. Based on the unequivocal relationship that
exists between the position of the points of reference 4 of the
wheel 2 and those of the coordinate system 11, is calculated the
corresponding position of the latter. In that way the correct
position of the wheel 2 relative to the frame 5 is known.
Besides the calculation of translatory displacements of the wheel 2
relative to the frame, this method can be also be used to determine
the orientation and rotation of the wheel 2 relative to the
stationary position or relative to the frame 5. By using, for the
points of reference 4, light-emitting diodes that produce a
wide-angled beam of light, or by using more than three points of
reference, very large excitations of the wheel 2 can be measured.
It is possible, therefore, to measure a rotation or an inclination
of the wheel 2 for angles which, for example, can range between 60
and 360 degrees for the three axes of the coordinate system 11.
Displacements relative to these axes can also be measured in the
order of several dozens of centimeters.
In another embodiment of the method, to which the invention
pertains, the position of the points of reference 4 of several
wheels 2 of the said vehicle 3 in a state of rest relative to one
another is measured as is the relative position of the points of
reference 4 of the frame.
Provision is also made for a central coordinate system 16 that is
reciprocating with respect to the frame 5 of the vehicle 3 and
which lies, for example, in the centre of gravity thereof. As a
consequence, any deformation of the frame 5 of the vehicle 3 is
determined by measuring the position of the various points of
reference 4 of this frame 5 in the vicinity of the wheels 2 and by
calculating the displacement thereof relative to this central
coordinate system 16 as and when these wheels are excited by the
actuators 1.
In a specific embodiment of the method, to which the invention
pertains, the position of the respective coordinate systems for the
wheels 2 is expressed in relative to the said central coordinate
system 16. Next, according to this embodiment of the method, the
relative displacement of the respective wheels 2, is, whenever
these wheels are excited, calculated, so as to study the dynamic
behaviour of the wheels 2 relative to one another. Any movements of
the wheels 2 can, like that, be measured relative to one
another.
The invention is, of course, not limited to the method as described
above. For example, more than three points of reference could be
incorporated and measured at each wheel 2. In addition, these
points of reference 4 and 6 could, for example, consist of all
manner of light sources such as, among other things, infrared LEDs.
If desired, the points of reference 4 and 6 could consist of a
colour-coded marking, markers or, alternatively, an arbitrary
identifying mark on a wheel or one the frame is used as a point of
reference.
If desired, still further points of reference could be added,
during the measurement itself, on the wheel or on the frame. To
that end, an additional point of reference is fitted to the wheel
or to the frame and the position of this extra point of reference
is measured and expressed relative to the position of the other
points of reference or relative to a shared system of
coordinates.
In addition to that, the said measuring system could also comprise
more than three cameras and these could be, for example, linear
cameras, matrix cameras or addressable cameras.
* * * * *